I would like to add my two cents to Chipp's very good tut.

I found that saving the z file directly from Vue in PSD format and choosing 16 bits, is more efficient than saving it in BMP. By using 16 bits in the z file, the transitions between shades of gray are softer and the lens blur effect in PS has a higher quality.

Sometimes, it's also necessary to smooth out the z file by applying a slight blur, before applying the lens blur to the main image. Otherwise, PS can create some artifacts in some transitions.